40 LOEWENFELD, Contribjitions to the History of Science. 



ments printed for the Philosophical Transactions, of 

 which one is for yourself, another for Dr. Darwin, and 

 the third for the gentleman who was so obliging as to 

 join you in contributing to the expense of my experi- 

 ments but wished to be unknown.'*' 



I am making the most of the fine sunshine we 

 now enjo)', and have lately discovered some very 

 remarkable new facts, which promise to throw much 

 new light on the doctrine of air, &;c. They could not 

 be made but by means of a burning lens. 



1 have been just trying a new process for pro- 

 curing the charcoals of the several metals, some of 

 which I shewed you, but it has not yet succeeded ; 

 but I do not despair, and I hope to do this and much 

 more, when I get a larger lens. As soon as I can get 

 a tolerable assortment of these new modifications of 

 the metals, I shall send them to you, either in London, 

 or at Etruria. 



I wish your business of application to Parliament 

 was in as good a train as my experiments are at 

 present. Your exertion, tho' unsuccessful, will do you 

 the greatest honour. 



With my respectful compliments to Mrs Wedg- 

 wood and your son, I am. Dear Sir, 



Yours sincerel}', 



J. Priestley. 

 The use of lenses for the production of high tempera- 

 tures was very common. It allowed. very clean work, and 

 the disturbing influence of the burning of coal as a means 

 of involuntary reduction was eliminated. The parlia- 

 mentary business of Wedgwood, to which allusion is 



■'•'^ About ih'-- many peojile who assisted Priestley by yearly allowances 

 or occasional gifts vide ' Memoirs,' p. 59. Priestly mentions in his 

 ' Appeal to the Public on the subject of the Riots in Birmingham ' (1791), 

 part ii., p. 105, that the Philosophical Society of Manchester had made 

 him a member and granted him ^<^o ' to assist me in defraying the costs of 

 my experiments.' 



